Reversing controller



Jun zs, 1927. 1,633,825

A. C. PRESCOTT REVERS ING CONTROLLER Filed Jan. 30. 1926 -L.l l

lnvenfdr Arthur C. Prescott Patented J une 28, 1927.

UNITEDST-ATES PATENT OFFICE.

an'rnun o. Pansco'rr, or EAST omen, NEWJERSEY, ASSIGNOB 'ro GENERAL ELBO- rnrc courm, A coaronarron or new YORK.

BEVERSI'NG CONTROLLER.

Application filled January 30, .1926. Serial No. 84,997.

My invention relates to improvementsjin controllers for electric motors and'in particular to improvements in controllers for periodically reversing an electric motor and protecting the motor during reversal. K Although not necessarily limited thereto, the invention has a particular application in the control of an electric motor driving a washing machine which is required to be periodically reversed. The invention is directed to features of construction and arrangement of a reversing controller whereby a comparatively few, simple and rugged parts are required for efiectin-g the reversal of the motor connections-with a snap action, controlling current limiting means to protect the motor during reversal, and for insuring that in case of failure of the source of supply for the motor the controller will not be damaged by the non-reversal of the motor as intended. i

For an understanding of the invention, reference is had to the accompanying drawing in which Fig. 1 is a perspective view of a controller in accordance with the invention,

Fig. 2 is a simplified diagram of a control system for an alternating current motor employing thecontroller of Fig. 1, and Fig.3 is a side'view of a washing machine employing an electric motor for driving the" same and a controller in accordance with the invention for periodically reversing the electric motor-to periodically reverse the washing machine. I

The controller comprises a set of contact mechanism arranged to effect the reversal of the connection of the motor to. the source of supply and a second set of contact mechanism 11 arranged to control current limiting means in the motor circuit so as to protect the motor during reversal. These two sets of contact mechanisms are operated by means of a common operating mechanism including the sprocket wheel 12 which is arranged to be driven by the electric motor to be controlled. This sprocket wheel operates thereciprocable arm which is mounted on. a shaft supported in the blbck 14 and which is connected through the sprocket wheel 12 by means of the slip clip 15. Thereversing contact mechanism 10 1s mounted on and insulated from an operating shaft 16,

and the star wheel 17 together with the resil-- .iently mounted detent arm 18 provides a means whereby the reversing contact mechanism is resiliently held in the position to which it has been last operated and whereby the reversal of the connection of the controlled motor to a source of supply is efiected .with a snap action movement of the reversin g contacts.

The second set of contact mechanism 11 is mounted on and insulated from a second shaft 19 which is of tubular form and disposed concentrically with the shaft 16., as

indicated in the drawing. The shaft 19 and the contact mechanism 11 are biased to the position indicated in the drawing, in which a circuit is established between the stationary contacts 20 and 21 through the segment 23 which cooperates with the pin carried by the support 31 for the shaft 19. The operating member 29 is secured to the shaft 19 in.

any suitable manner, so as to effect a limited rotation of the contact mechanism 11 in respouse to a limited movement of the operating member 29.

The shaft 16 which carries the reversing contact mechanism 10 is operated by means of the reciprocable arm 13 through a resilient driving connection including the arm 32 secured to the shaft 16 and a plate 33 mounted for rotation on the shaft 16 and carryingv a projection 34 on its periphery which is adapted to engage with the operating arm 13. The spring 35 provides a resilient connection between the arm 32 and the plate 33 and one end of this spring cooperates with a pin carried by the arm 32 and the other end of the spring cooperates with the pin carried by the plate 33.- The arrangement is such that byjmeans of this resilient driving connection and the biasing means including the star wheel 17 and the resilient detent 18, a limited movement of the plate. 33 is necessary beforea suflicient strain has been put on the spring 35 to move the reversing contact mechanism from one of its positions to another of its definite positions, and after this movement has been 7 through gearin is effective to operate the reversing contact mechanism with a snap action.

The reversing contact mechanism comprises a plurality of segments of the shape indicated in Fig. 1 and arranged to establish the electric circuits as indicated in Fig. 2, as will be later explained in connection with the operation of the system of Fig. 2. This mechanism cooperates with the two stationary contacts 36 and 37 mounted on one side of the shaft 16 and two stationary contacts 38 and 39 mounted on the other side of the shaft. The various parts heretofore referred to are suitably mounted on a support 40 and the various parts,,with the exception of the sprocket wheel 12, are arranged to be enclosed within a suitable casing as shown in Fig. 3.

As thus constructed and arranged and with the parts in their respective positions as indicated in Figs. 1 and 2, the operation of my invention for the control of a washing machine as indicated in Fig.3, is as follows:

The electric motor 41 is indicated as of the three phase alternating current type, although I would have it understood that the invention is not necessarily limited to'the control of an alternating current motor, but is likewise applicable to the control of other types of motors as well. ,The motor 41 is arranged to drive the washing machine 42 43 and the sprocket wheel 12 of the contrdller is arranged to be driven by means of the sprocket chain 44 operated by the electric motor through the washing machine. disconnecting switch 45 is first closed, thereby connecting the motor directly to the source of supply through the controller. One terminal of the motor is directly con- 7 nected to the source through the conductor 46, another terminal of the motor is connected to the source through the conductor 47, the stationary contact 20, the segment 23, the stationary contact 21, the stationary contact 36, the segment 48, segment 49 of the reversing contact mechanism and the stationary contact 38 to one of the phase conductors of the source of supply. The other terminal of the motor is connected through thestationary contact 24, the segment 26, stationary contact 25, stationary contact 39 of the reversing contact mechanism, segments 50 and 51 of the reversing contact mechanism and stationary contact 37 of this mechanism to the middle of the phase conductors of the source of supply.-

The motor will now operate in the proper direction until the limit of operation of the washing machine in this direction has been reached, the sprocket wheel 12 being now rotated in the counterclockwise direction until the arm 13 is brought into engagement with one of the arms on the member 29 which In order to start the motor, the.

tor circuits.

is secured to the shaft 19 for operating the contact mechanism 11. A continuation of the movement of the sprocket wheel in this direction will eifect a counterclockwise movement of the contact mechanism 11,. thereby.

opening the circuits through the segments 24 and 26 and including the resistors 52 and 53in the motor circuit for the purpose of limiting the current in the motor circuit during reversal,in order to protect the motor during this period. A continuation of the movement ofthe operating arm 13 will bring this arm into engagement with the projection 34 on the plate 33 and the spring 35 will 7 thus be put under a strain to throw the re-' arm 13 will continue in the counterclockwise direction until the direction of operation of the motor has been reversed by the electric braking effect caused by reversing the connection of the motor to the source of supply. During this interval the springs 27 and 35 will be put under a further strain. However, the reversal of the connection of the motor-to the source of supply effects such a comparatively great electric braking effeet,'that this further movement of the motor in the former direction will be comparatively slight. During the time that the reversal of the connection of the motor to the source of supply is effected, the resistors 52 and 53 are included in the motor circuits so as to protect the motor by limiting the current in the mo- The circuit for the motor will now be through the conductor 47, the resistor 52. segment 54 of the reversing contact mechanism, segment55 and contact 38 to the lower of the supply conductors. The other terminal of the motor is connected through the resistor 53, the segment 56 and the segment 57 of the reversing contact mechanism to the middle of the conductors of the source of supply. When the motor is thus brought to rest and begins rotation in the clockwise direction,-the sprocket wheel 12 will operate the arm 13 in the clockwise direction, thereby relieving the strain of the springs 27 and 35 and permitting these springs to resume their respective positions indicated in Fig. 1. The contact mechanism 11 will thus be effective to short-circuit the resistors 52 and 53 and connect the motor directly .in the source of supply for full speed operation. At the limit of this operation, the controller will be returned to the position. as indicated in Fig. 2, as will be understood from the foregoing.

In case for any reason the power supply should fail during the time in which the reversal of the connections of the motor to the source of supply is to be effected, the inertia effect of the washing machine will continue the rotation of the sprocket wheel 12 in the direction previously established, and to provide against the wrecking of the controller in case the power supply should thus fail, I have provided the slip clutch 15 which will slip when the strain set up in the springs 27 and 35 is in excess of a predetermined value so that the sprocket wheel 12 may continue in operationbeyond the limit intended, without producing any destructive effects: of the controller.

It will be observed that the controller has comparatively few and simple operating parts which are very easily assembled and which are of relatively rugged construction to withstand the comparatively severe service to which apparatus of this sort is ordinarily subjected. The reversal of the connection of the motor to the source of supply is effected with a snap action movement of the reversing contact mechanism 10, and the contact mechanism 11 controls the resistors 52 and 53st) as to effectively limit the cur rent of the motor circuit during the period of reversal so as to protect the motor during this period. The controller is protected from the destructive effects of a failure of power at or during the time in which the coritroller is intended to operate-to stop the motor and the driven machine by electric braking;

What I claimas new and desire to secure by Letters Patent of the United States, is,

1. A controller for periodically reversing an electric motor comprising reversing contact mechanism mounted for operation between two definite positions, relatively movable contact mechanism mounted for movement between two definite positions and biased to remain in one of said positions and to return thereto from the second position thereof, a common operating means for operating said contact mechanisms, and connectionsbetween the said means and said mechanisms through which the said second contact mechanism is operated from said first position to said second position, the said reversing mechanism then operated from its last operated position to its other position and the said second contact mechanism subsequently permitted toreturn to its first position.

2. A controller for periodically reversing an electric motor comprising a reciprocating operating member, reversing contact mechanism operable between two pos1tions, means for insuring a snap action of said mechations and biased to remain in one of the positions thereof and to return thereto from the second position thereof, a direct driving connection between said operating member and said second contact mechanism and a resilient driving connection between said reversing contact mechanism and said operat ing member.

3. A controller for periodically reversing an electric motor comprising two independently rotatable shafts one of which is journalled in the other, reversing contact mechanism operated by the first of said shafts be tween two positions, resilient biasing means for effecting a snap action movement of said mechanism and for holding said mechanism in the position to which last operated by said first shaft, 21 second contact mechanism. biased to one position and operated by the second of said shafts to a second position, a common operating means for said shafts, a direct driving connection between said second shaft and said operating means, and a resilient driving connection between said first shaft and said operating means.

4. A controller for periodically reversing the connection of an electric motor to asource of supply comprising a driving member, reciprocating reversing contact mechanism, the said mechanism being operable between two positions and being biased to the position to which last operated, a second relatively movable contact mechanism, the said second mechanism being biased to one position and operable to a second position, and operating connections between said driving member and said contact mechanisms including a device for limiting the value of the power transmitted through the connections.

5. A controller for periodically reversing an electric motor comprising reversing contact mechanism, the said mechanism being arranged to operate between two definite positions and biased to remain in the position to which last operated, a second contact mechanism operable between two posi tions and biased to remain in one of the positions and to return thereto from the second position, a common operating means for said contact mechanisms, connections between the said operating means and said mechanisms through which thesaid second contact mechanism is operated from said first position to said second position, the said reversing mechanism then operated from its last operated position to its other position and the said second contact mechanism subsequently permitted to return to its first position, and a slip clutch included in said connections to limit the power transmitted through said connections for operating said mechanisms.

6. In combination in a system of motor control, a motor, means for limiting the current in the motor circuit, and a controller for periodically reversing the connection of said motor to a source of supply and for controlling said current limiting means, the said controller being provided with a driving member connected to he rceiprocated by the motor, reversing switch contact mechanism included in the motor circuit, and a second indepenz'lentl movable conizu't mechanism for controlling said current limiting means, and connectlons between the said controller driving member and said contact mechanisms through which the said current limit-- ing means is rendered effective, the reversing contact mechanism then operated to reverse the connection of the motor to its source of supply and the second contact mechanism subsequently operated to render ineffective said current limiting means.

In Witness whereof, I have hereunto set my hand this 2Tth day of January, 1926.

Ali'li'llllt C. PRESCOTT. 

